000
FXUS64 KTSA 032152
AFDTSA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TULSA OK
352 PM CST TUE DEC 3 2013

.DISCUSSION...

WOW FOLKS...WHAT A FORECAST TODAY. THERE WILL BE SEVERAL ROUNDS OF
WINTRY PRECIPITATION THAT WILL HAVE IMPACTS ON TRAVEL AND POSSIBLY
THE POWER GRID AS WELL. I WILL DIVE INTO EACH FACET OF THE
FORECAST BELOW...ONE BY ONE.

FIRST...OF SOMEWHAT LESS IMPORTANCE...WILL BE FOG POTENTIAL
TONIGHT. FOR THE PAST 2 DAYS WE`VE HAD WIDESPREAD DENSE FOG.
TONIGHT...WHAT I SEE THAT IS DIFFERENT WILL BE THE DEPTH OF THE
NEAR GROUND MOIST LAYER. MODEL MOISTURE PROFILES DRY OUT FROM TOP
TO BOTTOM WITH TIME TONIGHT...ALTHOUGH THERE MAY BE ENOUGH REMNANT
MOISTURE NEAR THE GROUND FOR SOME PATCHY FOG DEVELOPMENT...SOME
POSSIBLY DENSE. FWIW...THE HRRR BREAKS OUT DENSE FOG OVER A GOOD
PORTION OF EASTERN OK THIS EVENING...AND IT HAS BEEN HANDLING THE
FOG WELL THE PAST 2 NIGHTS.

NOW TO THE MEAT OF THIS FORECAST. A VERY AMPLIFIED UPPER PATTERN
IS EVOLVING OVER THE WESTERN CONUS AS I TYPE...WITH A RIDGE NOSING
WELL UP INTO ALASKA...AND A DEEP POSITIVE TILT DOWNSTREAM TROUGH
DEVELOPING OVER THE WESTERN CONUS. THIS HAS CREATED A CROSS-POLAR
FLOW CLEAR FROM SIBERIA DOWN INTO NORTH AMERICA. WORSE YET...THIS
PATTERN WILL LIKELY PERSIST FOR ABOUT A WEEK...SENDING SHOT AFTER
SHOT OF ARCTIC AIR DOWN INTO THE CONUS AS DISTURBANCES ROTATE
AROUND THE POLAR VORTEX OVER CENTRAL CANADA. THE INITIAL SURGE OF
ARCTIC AIR WILL ARRIVE TOMORROW...AND WILL UNDERCUT A STRONG BELT
OF SW FLOW ALOFT DOWNSTREAM FROM THE WESTERN TROUGH. THE FIRST
ROUND OF PRECIP WILL BE FORCED MAINLY BY LOW TO MID LVL
FRONTOGENESIS...WHICH WILL KICK IN BY EARLY THURSDAY. THE MODELS
ARE IN VERY GOOD AGREEMENT ON A RATHER IMPRESSIVE BAND OF PRECIP
FROM SE OK UP INTO NRN AR ON THURSDAY. NE OK WILL BE ON THE FRINGE
OF THE BEST FN FORCING...AND WILL SEE LIGHTER PRECIP AMOUNTS AS A
RESULT. IN FACT...PORTIONS OF OSAGE COUNTY MAY NOT SEE ANYTHING
WITH THIS FIRST ROUND. NAM/GFS TEMP PROFILES SUGGEST THAT A BAND
OF SIGNIFICANT ICING IS POSSIBLE FROM SE OK UP INTO W CNTRL AR AND
PORTIONS OF NW AR. SOME PLACES HERE MAY PICK UP A QUARTER INCH OR
MORE OF ICE ACCUMULATION...WHICH COULD CAUSE POWER OUTAGES AND
SIGNIFICANT TRAVEL ISSUES. A BAND OF SIGNIFICANT SLEET
ACCUMULATION IS POSSIBLE JUST NORTH OF WHERE THE ZR/IP LINE SETS
UP...MOST LIKELY FROM E CNTRL AND EVENTUALLY PORTIONS OF SE OK
INTO W CNTRL AND NW AR AS THE COLDER AIR GETS DEEPER WITH TIME
FROM NORTH TO SOUTH. THIS COULD CAUSE SIGNIFICANT TRAVEL ISSUES AS
WELL. SOME LIGHT SNOW ACCUMULATION IS MOST LIKELY NEAR THE KANSAS
BORDER. THE FN FORCING SHIFTS SOUTHEAST BY THURSDAY EVENING AND
WEAKENS OVER OUR AREA...ENDING THE FIRST ROUND OF PRECIP.

ROUND TWO BEGINS LATE THURSDAY NIGHT INTO FRIDAY...AS A SHORTWAVE
TROUGH EJECTS EAST FROM THE WESTERN TROUGH OVER THE PLAINS. THE
INCREASING QG FORCING WILL BE MORE BROAD AND WILL COVER MORE OF
THE FORECAST AREA THIS GO AROUND. MODELS SUGGEST THAT A NICE WSW-
ENE ORIENTED DEFORMATION ZONE WILL SET UP FROM SOUTH CENTRAL INTO
NORTHEAST OK AND NORTHWEST AR. LAYER TEMP PROFILES FORECAST BY THE
GFS/ECMWF SUGGEST SNOW OR SNOW/SLEET FOR NE OK AND NW AR...WITH
MORE SLEET ACROSS MUCH OF SE OK AND W CNTRL AR. BASED ON QPF...THIS
COULD LEAD TO SEVERAL INCHES OF SNOW/SLEET ACCUMULATION.
HOWEVER...THE WARM NOSE MAY BE STRONG ENOUGH FOR MORE ZR AND THUS
ICE ACCUMULATION ACROSS FAR SE OK INTO W CNTRL AR LATE THURSDAY
NIGHT AS ROUND TWO GETS GOING. BY FRIDAY MORNING...THE WARM LAYER
IS ERODED ENOUGH FROM THE NORTH TO SHIFT THE BEST ICE POTENTIAL
SOUTH AND EAST OF THE FORECAST AREA. BOTH THE GFS/ECMWF SUGGEST
THAT THE QG FORCING WILL SHUT OFF RAPIDLY BY MIDDAY FRIDAY AS THE
WAVE SHEARS OUT AND LIFTS NORTHEAST OVER THE PLAINS. ROUND TWO
WILL LIKELY BRING MORE TRAVEL HEADACHES ACROSS A LARGER PORTION OF
THE FORECAST AREA. POWER INTERRUPTIONS EITHER MAY DEVELOP OR
CONTINUE OVER AREAS THAT HAVE RECEIVED THE MOST ICE ACCUMULATION
FROM THESE FIRST TWO ROUNDS OF PRECIP.

ROUND THREE GETS GOING OVER THE WEEKEND...AS ANOTHER SHORTWAVE
EMBEDDED WITHIN THE WESTERN CONUS LONGWAVE TROUGH EJECTS NORTHEAST
OVER THE PLAINS...AND A BIT FARTHER NORTH THAN THE PREVIOUS WAVE.
IN ADDITION...WITH THE SURFACE FRONT AND BEST MOISTURE NOW SHUNTED
WELL TO OUR SOUTH AND EAST...THERE WILL NOT BE AS MUCH MOISTURE
FOR THIS SYSTEM TO WORK WITH. INCREASING LOW/MID LVL ISENTROPIC
LIFT WILL RESULT IN AT LEAST LIGHT AMOUNTS OF PRECIPITATION
BEGINNING LATE SATURDAY AND INTO SUNDAY. MODEL SOUNDINGS ARE
FAIRLY DRY OVERALL IN THE CRUCIAL -10 TO -15C LAYER...WITH
MOISTURE MAINLY CONFINED BELOW 700MB. THIS WOULD SUGGEST THAT
PATCHY FREEZING DRIZZLE IS A POSSIBILITY AND HAS THUS BEEN ADDED
TO THE GRIDS. THERE ARE SOME HINTS OF PERIODIC MOISTENING DEEP
ENOUGH FOR ICE PRODUCTION...SO I HAVE ELECTED TO USE MULTIPLE
PRECIP TYPES IN THE GRIDS. THE GFS/ECMWF SUGGEST THAT THE WARM LAYER
WILL EXPAND NORTH INTO OUR AREA SOME DURING THIS TIME...AND THUS
ANOTHER ROUND OF MIXED PRECIP IS POSSIBLE...HOWEVER I WILL
REITERATE THAT PRECIP SHOULD REMAIN LIGHT OVERALL. THIS ROUND OF
PRECIP SHOULD END BY SUNDAY EVENING AS THE WARM CONVEYOR AND
RESULTING ISENTROPIC LIFT SHIFTS EAST OF OUR AREA.

FINALLY...BY EARLY NEXT WEEK THE GFS/ECMWF ARE IN GOOD AGREEMENT
THAT THE PERSISTENT WESTERN LONGWAVE TROUGH WILL LIFT OUT AND SHIFT
EAST OVER THE PLAINS. SOME LIFT AND LIMITED MOISTURE COULD SQUEEZE
OUT SOME LIGHT SNOW ON MONDAY. THIS SHOULD END WINTER PRECIP
CHANCES FOR THE TIME BEING...WHEW.

BOTTOM LINE...AN EXTENDED PERIOD OF VERY COLD WEATHER ALONG WITH
SEVERAL ROUNDS OF WINTRY PRECIPITATION ARE EXPECTED. TRAVEL WILL
BE AFFECTED...AND POWER DELIVERY MAY BE AS WELL IN SOME AREAS.
LOWS ON SATURDAY AND TUESDAY MORNING ARE EXPECTED TO DIP DOWN INTO
THE SINGLE DIGITS WITH WIND CHILLS BELOW ZERO OVER PORTIONS OF THE
AREA. GET READY FOLKS.

THE WINTER STORM WATCH WILL BE CONTINUED FOR THE ENTIRE FORECAST
AREA...WITH WARNINGS LIKELY TO FOLLOW EITHER TONIGHT OR WEDNESDAY.

LACY

&&

.PRELIMINARY POINT TEMPS/POPS...
TUL   44  49  28  28 /   0   0  20  70
FSM   48  66  37  37 /   0   0  20  90
MLC   46  59  33  33 /   0   0  20  90
BVO   40  45  26  27 /   0   0  10  60
FYV   47  60  31  31 /   0   0  20  90
BYV   49  62  30  30 /   0   0  20  90
MKO   45  56  31  31 /   0   0  20  90
MIO   45  50  26  27 /   0   0  10  90
F10   44  53  29  30 /   0   0  20  80
HHW   47  70  39  39 /   0   0  20  90

&&

.TSA WATCHES/WARNINGS/ADVISORIES...
OK...WINTER STORM WATCH FROM 6 AM THURSDAY TO 6 PM FRIDAY FOR OKZ054-
     OKZ055-OKZ056-OKZ057-OKZ058-OKZ059-OKZ060-OKZ061-OKZ062-
     OKZ063-OKZ064-OKZ065-OKZ066-OKZ067-OKZ068-OKZ069-OKZ070-
     OKZ071-OKZ072-OKZ073-OKZ074-OKZ075.

     WINTER STORM WATCH FROM NOON THURSDAY TO 6 PM FRIDAY FOR OKZ049-
     OKZ053-OKZ076.

AR...WINTER STORM WATCH FROM 6 AM THURSDAY TO 6 PM FRIDAY FOR ARZ001-
     ARZ002-ARZ010-ARZ011-ARZ019.

     WINTER STORM WATCH FROM NOON THURSDAY TO 6 PM FRIDAY FOR ARZ020-
     ARZ029.

&&

$$

LONG TERM....30